I opened the device and made it flash green/red again, then I uninstalled PiPlay v1.2.97 immediately without running it, and installed v220.127.116.11. The LED on the headset is now blue and this is what I see (After switching to Pimax Mode)
Now, when I cover the proximity sensor on the headset, the display turns on and shows the Pimax logo.
I ran some Steam games and....THE HEADSET IS FREAKIN WORKING!!! (Even though the serial number isn't showing correctly.)
MAN, I have to stress this important step again....DON'T RUN PIPLAY V1.X AFTER UP/DOWNGRADING THE FIRMWARE! IT WILL AUTOMATICALLY UPDATE THE FIRMWARE WHEN YOU RUN IT. UNINSTALL V1.X AND GET THE LATEST VERSION (In my case it's v18.104.22.168).
6 days in, still no response from the support. Can't imagine someone less technical go through this. Anyway, hope this thread helps any future readers.
EDIT: I updated the firmware through PiPlay v22.214.171.124 and everything is showing correctly now.